The clinical usefulness of the cannabinoids, including Δ9-tetrahydrocannabinol (Δ9-THC), to provide analgesia, help alleviate nausea and emesis, as well as stimulate appetite has been well-recognized. Cannabinoids offer a variety of pharmacological benefits, including, but not limited to, anti-spasmodic, anti-inflammatory, anti-convulsant, anti-psychotic, anti-oxidant, neuroprotective, anti-inflammatory, anti-cancer, and immunomodulatory effects.
Given the therapeutic benefit, it would be advantageous to develop a composition in which cannabinoids are delivered systemically to achieve a therapeutically effective dose. The cannabinoids undergo substantial first-pass metabolism when absorbed from the human gut after oral administration, which suggests alternate forms of dosage. It protects against the influx of toxins and the efflux of water and is largely impermeable to the penetration of foreign molecules, although small, lipophilic molecules can diffuse across the skin.
However, due to the protective function of the skin of a mammal, such as a human, even lipophilic and low molecular weight compounds generally only transfer in small amounts across the skin, resulting in difficulty in achieving therapeutic levels of drug in the bloodstream. Therefore, the success of transdermally administering therapeutically effective quantities of cannabinoids to a mammal in need of such treatment within a reasonable time frame and over a suitable surface area has been substantially limited.
The present invention is directed toward overcoming one or more of the problems discussed above.